I wish it only cost $500! By the time you get a cage and safety devices in the car (not counted in the $500 budget), tires, fuel, RV, tow fuel, food and the rest, it adds up fast.
That being said, "24 Hours of Lemons" still the cheapest and most fun wheel to wheel racing I've ever done. 4 hours of track time per driver is plenty in one weekend and it's still cheap considering what racing can cost. Plus the race organizer and staff are super nice and really try to make the event fun for all racers, fast and slow.
We are running another event in May. Will keep you all posted.